The present embodiments relate generally to a gas turbine engine. More particularly, but not by way of limitation, the present invention relates to a dirt separating accelerator which inhibits dust, dirt or other particulate passing through the turbine in the cooling air flowpaths and from entering the turbine rotor with the rotor cooling air.
A typical gas turbine engine generally possesses a forward end and an aft end with its several core or propulsion components positioned axially therebetween. An air inlet or intake is located at a forward end of the engine. Moving toward the aft end, in order, the intake is followed by a fan, a compressor, a combustion chamber, and a turbine. It will be readily apparent from those skilled in the art that additional components may also be included in the engine, such as, for example, low-pressure and high-pressure compressors, and low-pressure and high-pressure turbines. This, however, is not an exhaustive list.
The compressor and turbine generally include rows of airfoils that are stacked axially in stages. Each stage includes a row of circumferentially spaced stator vanes and a row of rotor blades which rotate about a center shaft or axis of the turbine engine. A multi-stage low pressure turbine follows the multi-stage high pressure turbine and is typically joined by a second shaft to a fan disposed upstream from the compressor in a typical turbo fan aircraft engine configuration for powering an aircraft in flight.
The stator is formed by a plurality of nozzle segments which are abutted at circumferential ends to form a complete ring about the axis of the gas turbine engine. Each nozzle segment may comprise one or more vanes, which extend between an inner band and an outer band.
A typical gas turbine engine utilizes a high pressure turbine and low pressure turbine to maximize extraction of energy from high temperature combustion gas. The turbine section typically has an internal shaft axially disposed along a center longitudinal axis of the engine. The blades are circumferentially distributed on a rotor causing rotation of the internal shaft. The internal shaft is connected to the rotor and the air compressor, such that the turbine provides a rotational input to the air compressor to drive the compressor blades. As the combustion gas flows downstream through the turbine stages, energy is extracted therefrom and the pressure of the combustion gas is reduced.
In operation, air is pressurized in a compressor and mixed with fuel in a combustor for generating hot combustion gases which flow downstream through turbine stages. These turbine stages extract energy from the combustion gases. A high pressure turbine first receives the hot combustion gases from the combustor and includes a stator nozzle assembly directing the combustion gases downstream through a row of high pressure turbine rotor blades extending radially outwardly from a supporting rotor disk. The stator nozzles turn the hot combustion gas in a manner to maximize extraction at the adjacent downstream turbine blades. In a two stage turbine, a second stage stator nozzle assembly is positioned downstream of the first stage blades followed in turn by a row of second stage rotor blades extending radially outwardly from a second supporting rotor disk. The turbine converts the combustion gas energy to mechanical energy.
Dust accumulation and plugging of cooled turbine blades causes reduced airfoil durability and premature performance deterioration in part by increased tip clearances and airfoil distress. This deterioration is particularly notable in environments which are dusty or include large amounts of sand, such as deserts or arid regions.
Operators who fly or utilize turbine technology in these regions historically have early engine deterioration or distress due to the abundance of particulate dust or dirt in the air. This results in engine downtime sooner than a normal maintenance interval.
It would be desirable to overcome these and other deficiencies by improving turbine blade durability. It would also be desirable to extend the operating life of the engines which may be shortened due to operation in these dirty regions of the world. Further, it would be desirable to reduce the amount of dirt or dust that enters the turbine cooling air supply system, or the blade cooling circuit, so that the blade cooling circuit is less likely to be plugged with dirt, avoiding over temperature of the blade, blade distress and eventually engine deterioration.
It would be desirable to overcome these and other deficiencies with gas turbine engines and more specifically it would be desirable to inhibit dust and dirt from entering a rotor cooling circuit within a gas turbine engine.